#1 CM Punk

It would seem that no matter how fragmented a relationship former Superstars have with WWE, they always come back in the end. It happened with Bret Hart, Bruno Sammartino, and Ultimate Warrior returned just in time to be inducted into the Hall of Fame before he passed away.
When it comes to CM Punk, however, the "Straight Edge Superstar" may very well be the exception to that rule. Since storming out of WWE, Punk has ventured into UFC and also dabbled in writing for Marvel and seems perfectly happy without wrestling in his life.
Did you know a top WWE Superstar just wrestled outside the company? More details HERE
It isn't just WWE he has a problem with either. A British wrestling company reportedly offered the Second City Saint $1 million to come and perform for them, but he had no interest. It would seem that WWE have killed Punk's love of pro wrestling and he may very well never return to the business.